By Matthew Fitzsimmons

In 2014, Pennsylvania discovered a new invasive insect – the spotted lanternfly (SLF). Native to east Asia, the SLF likely arrived on cargo arriving in Philadelphia. It’s since spread to 15 states along the East Coast, including a number of counties in northern and central Virginia.

This insect is harmless to humans but can damage many tree species, ornamental plants, and economically important crops. According to the Virginia Department of Agriculture, left unchecked, the SLF can reduce grape harvests by 90%, making them especially dangerous to local viticulture.

The spotted lanternfly inflicts damage by sucking the sap out of vines. They also excrete a sugary substance called honeydew. Honeydew attracts nuisance insects and causes the growth of a sooty mold which inhibits photosynthesis. This mold can also cover manmade structures and can be difficult to remove, making the SLF a pest for homeowners as well.

Technically the spotted lanternfly isn’t even a fly; it’s a planthopper. These species of insects can’t fly very far. Instead, they spread by hitchhiking on unwitting vectors to find new feeding grounds.

This has spurred a number of states to declare counties with high concentrations of spotted lanternfly as quarantine areas, and mandate certain businesses operating within them to acquire permits which certify they have a working knowledge of how to prevent the SLF’s expansion.

2023 a “dress rehearsal” for next year’s invasion

“I imagine this coming year, or the one after, will be the real start of the war against the spotted lanternfly in the vineyard,” Mountain Run Winery owner David Foster explained in an email.

As the spotted lanternfly doesn’t have native predators, vineyard owners must rely upon an integrated pest management system of traps and pesticides. These solutions only go so far, however, making prevention their preferred strategy. This includes removing the SLF’s favorite host, the tree of heaven (Ailanthus altissima).

Unfortunately, the latter is easier said than done. This tree has an aggressive root system and cutting down one tree will only spur new growth. Even if these trees are removed, other food sources for the spotted lanternfly are available.

Winemaker Preston Thomas of Stone Tower Winery explained his strategy.

“For SLF, we are prepared to mitigate them at all critical points of the year. We’ve already begun going through our vineyard blocks and identifying where we see egg sacs and eliminating them.

Once we get to next spring, we will be setting traps to track the nymph emergence, at which point we will spray an insecticide to exterminate them. The crucial aspect of mitigating SLF is ensuring we nail the timing to catch them at the appropriate stage for spray efficacy.

Navigating SLF has been, and will continue to be, a collaborative effort between all growers in Virginia and the mid-Atlantic. Sharing information about strategies and successes is vital for ensuring positive outcomes as a premium grape growing region.”

For other vineyards, SLF preparations have already moved from a “dress rehearsal” to an immediate threat.

“Last year we saw roughly 20 adult lanternflies in traps and around a few buildings,” wrote Scott Spelbring of Bluemont Vineyard. “This spring we started seeing nymphs and carefully watched for more. It was more concerning than alarming.

But by mid-September we started to see adults move from the tree line to the vineyard. Now, it’s a full-on invasion.”

What Virginia Residents Can Do

If you find a spotted lanternfly – kill it! Stomp them, squish them, smash them however you like. You should also scrape egg masses found attached to trees, which can be found between late fall to early spring. But use insecticides judiciously, as they are unlikely to remove the SLF from the environment.

If you’re in an area not under quarantine and see one of these pests, be sure to take a photo of the offender and report it online at the Virginia Cooperative Extension website or contact spottedlanternfly@vdacs.virginia.gov. Residents in quarantined areas no longer need to report them.

While wine growers don’t want to downplay the threat, they also want to put it into perspective. Other invasive insects, such as Japanese beetles, have caused scares in the past, only for their populations to crash as nature comes back into balance.

“I think Pennsylvania is far enough into this issue that we can learn from them and will manage it just fine,” said Jason Murray of Arterra Wines.

About the Author: Matthew Fitzsimmons is a blogger who has visited nearly every winery in Virginia – most of them twice. Track his progress at https://winetrailsandwanderlust.com/